watch the air cells in them, i have a hydrometer and all but i am still going to candle them to make sure everythings going right. i have one black copper marans in as a tester for my bator (dont know if its furtil or not) that i candled tonight and its hard to see through but i think it might just be furtil...oh no that means it will hatch before my other eggs will, i wont be setting them till sunday!!!! i only have one bator and i'm not going to just take it out...its hatch date is nov 2nd while the rest will bne nov. 7.
just because they didnt devolop doesnt mean it was you since they were shipped they might have been srcambled, plus shipped eggs have to go through x-rays rough handling and temp changes on the way to your bator. if these are your own and they werent shipped i'm sure you will have better luck at hatching them as they didnt have to go through what shipped eggs do. just dont give up and if you have to wait, do more research in that waiting period so you know you will be ready. if these dont hatch try opening them and taking pics and posting here i'm sure people here would be glad to help you so you know what happened this time...did you open any of the last ones you tried to hatch and if so could you describe what you saw in the eggs?